The charity known as the Design Industries Foundation Fighting AIDS, or Diffa, turned 30 in April.

Its first fund-raiser, recalled Pat Green, a textile designer and one of Diffa’s founders (along with Larry Pond, who died in 1992, and others), was just a couple of jars on a table in the Architects and Designers Building. The few hundred dollars gathered there went to help sick friends and strangers pay their rent or Con Ed bills, as they became unable to work, or to fly in family members, when they began to die.

Since then, with ever-more sophisticated events, like the Love Ball and Dining by Design, an extravaganza at which designers create themed tables, Diffa has raised more than $40 million, which it has disbursed in grants to hundreds of organizations, including the Gay Men’s Health Crisis, God’s Love We Deliver and Alpha Workshops, which teaches artisanal skills to men and women with the disease.

To mark Diffa’s birthday, which happened to coincide with the 30th anniversary of the Rockwell Group, the architect David Rockwell, who was the chairman of Diffa from 2000 until last year, and Cindy Allen, editor of Interior Design magazine and the charity’s new chairwoman, hosted an event on May 28 at the NeueHouse on East 25th Street.

Among the kilims and cowhides, the tufted sofas and 1940s-era office chairs of the place, a work space collective designed by Mr. Rockwell, there was Johanna Osburn, Diffa’s new director, just 36 years old and a former activist and fund-raiser with the Empire State Pride Agenda. Her mandate, she said, is to educate a generation that believes itself immune to a disease that still infects about 50,000 Americans each year, according to the federal Centers for Disease Control and Prevention; in 2011, 26 percent of new infections were in individuals from ages 13 to 34.

David Sheppard, 68, who had been Diffa’s executive director for 18 years, was down from his house in Margaretville, N.Y., with his dog, Spot, holed up, as Mr. Rockwell said, “in Pod 39, the dog-friendly hotel we had to find for him.” In the mid-1980s, Mr. Sheppard was an Atlanta-based interior designer when he saw an ad for Diffa in Interiors magazine.

“Imagine a full page of people lined up on the steps of some building,” he said. “I recognized architects, designers, editors. But I didn’t realize there wasn’t some huge organization behind them. It was just well-meaning people.”

He added: “I knew I wasn’t strong enough to be a caregiver, but I knew I could raise money.”

His first event, Heart Strings, at the Fox Theater in Atlanta, raised $125,000.

The night’s focus was a panel discussion led by Ms. Allen, with Ruben and Isabel Toledo, the Cuban illustrator and fashion designer; the playwright Terrence McNally; and Jamie Drake, the interior designer, all of whom spoke of how the disease affected their industries in those early, terrifying years.

Mr. Rockwell, whose brother Rick died of AIDS in 1993, said: “Rick’s death made me feel helpless and hopeless. Like all of us here, I wanted to channel that grief and energy.” Designers, he added, are really good at solving problems. He called the creative community the disease’s first responders.

Mr. McNally, whose long career has included many notable works with AIDS- and gay-related themes, like his most recent play, “Mothers and Sons,” recalled the first production, in 1985, of his play “The Lisbon Traviata,” and how its star at the time, Seth Allen, wouldn’t dress in front of the other actors because, as Mr. McNally later learned, Mr. Allen had developed lesions. He died a year later.

“AIDS revealed gaping wounds,” Mr. McNally said. “It revealed how deep homophobia ran in this country. There was so much secrecy. You were calling people’s parents, people who weren’t out yet, and having to say, ‘Your son is gay, and your son is dead.’ ”

Ms. Allen asked Mr. McNally, “Are your parents proud of you?”

Only, he said wryly, “if I won a Tony. Otherwise, it’s ‘Why do you have to write another play about them?’ Mom, I am them.” He wiped his eyes, startled by sudden tears. “You can ask my husband, I never cry.”

Mr. Drake recalled his first year in New York City at Parsons School of Design. It was 1975, and his two dorm mates, Keith Emard and Kevin Bocash, both in the fashion department, became his best friends. By 1987, Mr. Emard would be dead. Mr. Bocash died in 1992.

The Toledos, who are both 53 and who have defined a vibrant, if ever shrinking, part of Manhattan’s demimonde for longer than Diffa has been in existence, celebrated their 30th wedding anniversary this year. And Mr. Toledo’s whimsical and exuberant illustrations have defined Diffa events from the beginning.

“We were just kids in the trenches,” Mr. Toledo said of those early years, “trying to help our friends pay the rent, cook their meals. You felt like they were slipping into the ocean, and you couldn’t hold on to them. It was happening to all of us.”

Earlier in the evening, he had reminisced about his gang at the time: the performer Joey Arias; Keith Haring, who would be dead of AIDS by 1990; Kenny Scharf; and Kim Hastreiter, editor of Paper magazine, which also began in 1984. “We were like the Little Rascals,” he said. “AIDS was part of us, but at first we didn’t know what it was.”

Mr. Toledo recalled playing cymbals for Klaus Nomi, the spectral, campy German New Age opera star who died of AIDS in 1983, one of the first public figures to be felled. Mr. Toledo described one memorable night at Hurrah’s, a club on West 62nd Street, when Mr. Nomi performed after Madonna, then a budding club star. Mr. Haring was in the audience with Mr. Scharf, both armed with flashlights that they shined on the performers’ crotches. “They were very naughty,” Mr. Toledo said, shaking his head.

And there was hair spray everywhere, he added, because “Debi Mazar was trying to get that hair of Madonna’s higher and bigger. Klaus said, ‘I can’t sing with all this aerosol.’ Of course, he never sang better.”